Will be doing some field work starting tomorrow until the 9th of August, so enjoy your weekly dose of dinosaurs a day early!
Series should resume as usual once I get back.
Pronounced Jig-uh-no-to-sor-ihs.
This is Giganotosaurus, a massive theropod dinosaur native to the ancient 98 million year old winding river systems in the now largely desert area of southern Argentina.
Giganotosaurus is a member of a group of enormous carnivorous dinosaurs known as the Caracharodontosauridae, who take its name from the African dinosaur (and first discovered member of the group) Carcharodontosaurus (or 'shark-toothed lizard').
Because the majority of the Carcharodontosaurids are found in Gondwana (the ancient super continent comprising modern day Africa, South America, India, Madagascar, New Zealand, Australia, and Antarctica) little is known about the group compared to its more northern (and far more well studied) counterparts.
Though they are closely related, evolution took different directions in both Giganotosaurus and Carcharodontosaurus due to an evolutionary phenomenon called 'vicariance' .
At one point in time, Africa and South America were merged as a portion of one much larger (and universal) continent called Pangea--during this time, dinosaur diversity was almost non-existent--the climate was uniform, with nearly the whole continent covered with desert. There were few if any mountain ranges and little water, which kept the dinosaur populations continuously intermixing.
However, over time the continent began to split--first in a north/south direction with Laurasia (North America/Europe/Asia) breaking off and floating northward. Later, southern Gondwana began to fragment with the Tethys seaway forming between Africa and South America.
It was this seaway that lead to the geographic isolation of the ancestors of Giganotosaurus and Carcharodontosaurus. These isolated biological conditions are what causes vicariance--populations become cut off, and go in their own evolutionary direction.
To give a pretty neat visual example, this is the skull of the African Carcharodontosaurus--
And this is the skull of South American Giganotosaurus--
One of the most distinctive differences in two dimensions (without being able to show a 3d skull) lies in the shape of the second bone from the left of the upper jaw called the Maxilla--in Carcharodontosaurus, it starts out very large and rounded on the left side and rapidly decreases in size as it moves to the right.
But in Giganotosaurus, it's practically one huge rectangular block!
A block which happens to be contained in the largest dinosaur skull recorded--though the original find (the 'holotype' of which all comparative discoveries are based on) was slightly smaller, a fragment of the lower jaw or 'dentary' was uncovered that belonged to an absolutely titanic skull.
In total, Gigonotosaurus had a skull six foot three inches long, pretty imposing stuff when you combine its estimated length of 41 feet.
Hope you enjoy, and feel free to rec away!
Regular series will resume on the 12th of August once I get back from the field--with luck I'll have photos and a few stories to share!
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